Re: [PATCH v2 08/16] arm/arm64: KVM: Advertise SMCCC v1.1

From: Russell King - ARM Linux
Date: Mon Jan 29 2018 - 19:23:47 EST

On Mon, Jan 29, 2018 at 05:45:51PM +0000, Marc Zyngier wrote:
> The new SMC Calling Convention (v1.1) allows for a reduced overhead
> when calling into the firmware, and provides a new feature discovery
> mechanism.
>
> Make it visible to KVM guests.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> Documentation/virtual/kvm/arm/psci.txt | 12 +++++++-----
> arch/arm/kvm/handle_exit.c | 2 +-
> arch/arm64/kvm/handle_exit.c | 2 +-
> include/kvm/arm_psci.h | 2 +-
> include/linux/arm-smccc.h | 13 +++++++++++++
> virt/kvm/arm/psci.c | 24 +++++++++++++++++++++++-
> 6 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/arm/psci.txt b/Documentation/virtual/kvm/arm/psci.txt
> index 2e49a4e9f084..aafdab887b04 100644
> --- a/Documentation/virtual/kvm/arm/psci.txt
> +++ b/Documentation/virtual/kvm/arm/psci.txt
> @@ -13,7 +13,7 @@ a migration causes a different PSCI version to be exposed out of the
> blue to an unsuspecting guest.
>
> In order to remedy this situation, KVM exposes a set of "firmware
> -pseuodo-registers" that can be manipulated using the GET/SET_ONE_REG
> +pseudo-registers" that can be manipulated using the GET/SET_ONE_REG

This should surely be in patch 7?

> interface. These registers can be saved/restored by userspace, and set
> to a convenient value if required.
>
> @@ -21,8 +21,10 @@ The following register is defined:
>
> * KVM_REG_ARM_PSCI_VERSION:
>
> - - Only valid if the vcpu has KVM_ARM_VCPU_PSCI_0_2 feature set
> - - Returns the current PSCI version on GET_ONE_REG
> - - Allows any supported PSCI version compatible with v0.2 to be set
> - with SET_ONE_REG
> + - Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set
> + (and thus has already been initialized)
> + - Returns the current PSCI version on GET_ONE_REG (defaulting to the
> + highest PSCI version implemented by KVM and compatible with v0.2)
> + - Allows any PSCI version implemented by KVM and compatible with
> + v0.2 to be set with SET_ONE_REG
> - Affects the whole VM (even if the register view is per-vcpu)
> diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
> index e020cc82c4b1..a4520c7118d2 100644
> --- a/arch/arm/kvm/handle_exit.c
> +++ b/arch/arm/kvm/handle_exit.c
> @@ -36,7 +36,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> kvm_vcpu_hvc_get_imm(vcpu));
> vcpu->stat.hvc_exit_stat++;
>
> - ret = kvm_psci_call(vcpu);
> + ret = kvm_hvc_call_handler(vcpu);
> if (ret < 0) {
> vcpu_set_reg(vcpu, 0, ~0UL);
> return 1;
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 97e8d64a203d..bb6e1518d819 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -52,7 +52,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> kvm_vcpu_hvc_get_imm(vcpu));
> vcpu->stat.hvc_exit_stat++;
>
> - ret = kvm_psci_call(vcpu);
> + ret = kvm_hvc_call_handler(vcpu);
> if (ret < 0) {
> vcpu_set_reg(vcpu, 0, ~0UL);
> return 1;
> diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
> index f2fa7d752c4e..4876bfac2195 100644
> --- a/include/kvm/arm_psci.h
> +++ b/include/kvm/arm_psci.h
> @@ -26,7 +26,7 @@
> #define KVM_ARM_PSCI_LATEST KVM_ARM_PSCI_1_0
>
> int kvm_psci_version(struct kvm_vcpu *vcpu);
> -int kvm_psci_call(struct kvm_vcpu *vcpu);
> +int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
>
> struct kvm_one_reg;
>
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 4c5bca38c653..dc68aa5a7261 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -60,6 +60,19 @@
> #define ARM_SMCCC_QUIRK_NONE 0
> #define ARM_SMCCC_QUIRK_QCOM_A6 1 /* Save/restore register a6 */
>
> +#define ARM_SMCCC_VERSION_1_0 0x10000
> +#define ARM_SMCCC_VERSION_1_1 0x10001
> +
> +#define ARM_SMCCC_VERSION_FUNC_ID \
> + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
> + ARM_SMCCC_SMC_32, \
> + 0, 0)
> +
> +#define ARM_SMCCC_ARCH_FEATURES_FUNC_ID \
> + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
> + ARM_SMCCC_SMC_32, \
> + 0, 1)
> +
> #ifndef __ASSEMBLY__
>
> #include <linux/linkage.h>
> diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
> index 682f9be6264b..3bb336ac7d7d 100644
> --- a/virt/kvm/arm/psci.c
> +++ b/virt/kvm/arm/psci.c
> @@ -15,6 +15,7 @@
> * along with this program. If not, see <http://www.gnu.org/licenses/>.
> */
>
> +#include <linux/arm-smccc.h>
> #include <linux/preempt.h>
> #include <linux/kvm_host.h>
> #include <linux/uaccess.h>
> @@ -353,6 +354,7 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
> case PSCI_0_2_FN_SYSTEM_OFF:
> case PSCI_0_2_FN_SYSTEM_RESET:
> case PSCI_1_0_FN_PSCI_FEATURES:
> + case ARM_SMCCC_VERSION_FUNC_ID:
> val = 0;
> break;
> default:
> @@ -407,7 +409,7 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
> * Errors:
> * -EINVAL: Unrecognized PSCI function
> */
> -int kvm_psci_call(struct kvm_vcpu *vcpu)
> +static int kvm_psci_call(struct kvm_vcpu *vcpu)
> {
> switch (kvm_psci_version(vcpu)) {
> case KVM_ARM_PSCI_1_0:
> @@ -421,6 +423,26 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
> };
> }
>
> +int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> +{
> + u32 func_id = smccc_get_function(vcpu);
> + u32 val;
> +
> + switch (func_id) {
> + case ARM_SMCCC_VERSION_FUNC_ID:
> + val = ARM_SMCCC_VERSION_1_1;
> + break;
> + case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
> + val = -1; /* Nothing supported yet */
> + break;
> + default:
> + return kvm_psci_call(vcpu);
> + }
> +
> + smccc_set_retval(vcpu, val, 0, 0, 0);
> + return 1;
> +}
> +
> int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> {
> return 1; /* PSCI version */
> --
> 2.14.2
>
>
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> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

--
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